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Date: Fri, 08 Jul 2022 09:58:33 +0100
From: Marc Zyngier <maz@...nel.org>
To: Frank Li <Frank.Li@....com>
Cc: tglx@...utronix.de, robh+dt@...nel.org,
krzysztof.kozlowski+dt@...aro.org, shawnguo@...nel.org,
s.hauer@...gutronix.de, kw@...ux.com, bhelgaas@...gle.com,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-pci@...r.kernel.org,
peng.fan@....com, aisheng.dong@....com, jdmason@...zu.us,
kernel@...gutronix.de, festevam@...il.com, linux-imx@....com,
kishon@...com, lorenzo.pieralisi@....com, ntb@...ts.linux.dev
Subject: Re: [PATCH 1/3] irqchip: imx mu worked as msi controller
On Thu, 07 Jul 2022 22:02:36 +0100,
Frank Li <Frank.Li@....com> wrote:
>
> MU support generate irq by write data to a register.
> This patch make mu worked as msi controller.
> So MU can do doorbell by using standard msi api.
>
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
> drivers/irqchip/Kconfig | 7 +
> drivers/irqchip/Makefile | 1 +
> drivers/irqchip/irq-imx-mu-msi.c | 490 +++++++++++++++++++++++++++++++
> 3 files changed, 498 insertions(+)
> create mode 100644 drivers/irqchip/irq-imx-mu-msi.c
>
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index 5e4e50122777d..4599471d880c0 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -470,6 +470,13 @@ config IMX_INTMUX
> help
> Support for the i.MX INTMUX interrupt multiplexer.
>
> +config IMX_MU_MSI
> + bool "i.MX MU work as MSI controller"
> + default y if ARCH_MXC
> + select IRQ_DOMAIN
> + help
> + MU work as MSI controller to do general doorbell
> +
> config LS1X_IRQ
> bool "Loongson-1 Interrupt Controller"
> depends on MACH_LOONGSON32
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index 5d8e21d3dc6d8..870423746c783 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -98,6 +98,7 @@ obj-$(CONFIG_RISCV_INTC) += irq-riscv-intc.o
> obj-$(CONFIG_SIFIVE_PLIC) += irq-sifive-plic.o
> obj-$(CONFIG_IMX_IRQSTEER) += irq-imx-irqsteer.o
> obj-$(CONFIG_IMX_INTMUX) += irq-imx-intmux.o
> +obj-$(CONFIG_IMX_MU_MSI) += irq-imx-mu-msi.o
> obj-$(CONFIG_MADERA_IRQ) += irq-madera.o
> obj-$(CONFIG_LS1X_IRQ) += irq-ls1x.o
> obj-$(CONFIG_TI_SCI_INTR_IRQCHIP) += irq-ti-sci-intr.o
> diff --git a/drivers/irqchip/irq-imx-mu-msi.c b/drivers/irqchip/irq-imx-mu-msi.c
> new file mode 100644
> index 0000000000000..f7193a6c1245e
> --- /dev/null
> +++ b/drivers/irqchip/irq-imx-mu-msi.c
> @@ -0,0 +1,490 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * NXP MU worked as MSI controller
> + *
> + * Copyright (c) 2018 Pengutronix, Oleksij Rempel <o.rempel@...gutronix.de>
> + * Copyright 2022 NXP
> + * Frank Li <Frank.Li@....com>
> + * Peng Fan <peng.fan@....com>
> + *
> + * Based on drivers/mailbox/imx-mailbox.c
> + */
> +#include <linux/clk.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/msi.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/irqdomain.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_pci.h>
> +#include <linux/of_platform.h>
> +#include <linux/spinlock.h>
> +#include <linux/dma-iommu.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/pm_domain.h>
> +
> +
> +#define IMX_MU_CHANS 4
> +
> +enum imx_mu_chan_type {
> + IMX_MU_TYPE_TX, /* Tx */
> + IMX_MU_TYPE_RX, /* Rx */
> + IMX_MU_TYPE_TXDB, /* Tx doorbell */
> + IMX_MU_TYPE_RXDB, /* Rx doorbell */
What does any of this even mean for MSIs?
> +};
> +
> +enum imx_mu_xcr {
> + IMX_MU_GIER,
> + IMX_MU_GCR,
> + IMX_MU_TCR,
> + IMX_MU_RCR,
> + IMX_MU_xCR_MAX,
> +};
> +
> +enum imx_mu_xsr {
> + IMX_MU_SR,
> + IMX_MU_GSR,
> + IMX_MU_TSR,
> + IMX_MU_RSR,
> +};
> +
> +enum imx_mu_type {
> + IMX_MU_V1,
> + IMX_MU_V2,
> + IMX_MU_V2_S4 = BIT(15),
If the bit assignment is significant, make it so for all members of
this enum.
> +};
> +
> +/* Receive Interrupt Enable */
> +#define IMX_MU_xCR_RIEn(type, x) (type & IMX_MU_V2 ? BIT(x) : BIT(24 + (3 - (x))))
> +#define IMX_MU_xSR_RFn(type, x) (type & IMX_MU_V2 ? BIT(x) : BIT(24 + (3 - (x))))
> +
> +struct imx_mu_dcfg {
> + enum imx_mu_type type;
> + u32 xTR; /* Transmit Register0 */
> + u32 xRR; /* Receive Register0 */
> + u32 xSR[4]; /* Status Registers */
> + u32 xCR[4]; /* Control Registers */
> +};
> +
> +struct imx_mu_msi {
> + spinlock_t lock;
> + struct platform_device *pdev;
> + struct irq_domain *parent;
> + struct irq_domain *msi_domain;
> + void __iomem *regs;
> + phys_addr_t msiir_addr;
> + struct imx_mu_dcfg *cfg;
> + u32 msir_num;
> + struct imx_mu_msir *msir;
> + u32 irqs_num;
> + unsigned long used;
> + u32 gic_irq;
> + struct clk *clk;
> + struct device *pd_a;
> + struct device *pd_b;
> + struct device_link *pd_link_a;
> + struct device_link *pd_link_b;
> +};
> +
> +static void imx_mu_write(struct imx_mu_msi *msi_data, u32 val, u32 offs)
> +{
> + iowrite32(val, msi_data->regs + offs);
> +}
> +
> +static u32 imx_mu_read(struct imx_mu_msi *msi_data, u32 offs)
> +{
> + return ioread32(msi_data->regs + offs);
> +}
> +
> +static u32 imx_mu_xcr_rmw(struct imx_mu_msi *msi_data, enum imx_mu_xcr type, u32 set, u32 clr)
> +{
> + unsigned long flags;
> + u32 val;
> +
> + spin_lock_irqsave(&msi_data->lock, flags);
> + val = imx_mu_read(msi_data, msi_data->cfg->xCR[type]);
> + val &= ~clr;
> + val |= set;
> + imx_mu_write(msi_data, val, msi_data->cfg->xCR[type]);
> + spin_unlock_irqrestore(&msi_data->lock, flags);
> +
> + return val;
> +}
> +
> +static void imx_mu_msi_mask_irq(struct irq_data *data)
> +{
> + struct imx_mu_msi *msi_data = irq_data_get_irq_chip_data(data->parent_data);
> +
> + pci_msi_mask_irq(data);
What is this? Below, you create a platform MSI domain. Either you
support PCI, and you create a PCI/MSI domain (and the above may make
sense), or you are doing platform MSI, and the above is non-sense.
> + imx_mu_xcr_rmw(msi_data, IMX_MU_RCR, 0, IMX_MU_xCR_RIEn(msi_data->cfg->type, data->hwirq));
> +}
> +
> +static void imx_mu_msi_unmask_irq(struct irq_data *data)
> +{
> + struct imx_mu_msi *msi_data = irq_data_get_irq_chip_data(data->parent_data);
> +
> + pci_msi_unmask_irq(data);
> + imx_mu_xcr_rmw(msi_data, IMX_MU_RCR, IMX_MU_xCR_RIEn(msi_data->cfg->type, data->hwirq), 0);
> +}
> +
> +static struct irq_chip imx_mu_msi_irq_chip = {
> + .name = "MU-MSI",
> + .irq_mask = imx_mu_msi_mask_irq,
> + .irq_unmask = imx_mu_msi_unmask_irq,
> +};
> +
> +static struct msi_domain_ops its_pmsi_ops = {
> +};
> +
> +static struct msi_domain_info imx_mu_msi_domain_info = {
> + .flags = (MSI_FLAG_USE_DEF_DOM_OPS |
> + MSI_FLAG_USE_DEF_CHIP_OPS |
> + MSI_FLAG_PCI_MSIX),
> + .ops = &its_pmsi_ops,
> + .chip = &imx_mu_msi_irq_chip,
> +};
> +
> +static void imx_mu_msi_compose_msg(struct irq_data *data, struct msi_msg *msg)
> +{
> + struct imx_mu_msi *msi_data = irq_data_get_irq_chip_data(data);
> +
> + msg->address_hi = upper_32_bits(msi_data->msiir_addr);
> + msg->address_lo = lower_32_bits(msi_data->msiir_addr + 4 * data->hwirq);
> + msg->data = data->hwirq;
> +
> + iommu_dma_compose_msi_msg(irq_data_get_msi_desc(data), msg);
> +}
> +
> +static int imx_mu_msi_set_affinity(struct irq_data *irq_data,
> + const struct cpumask *mask, bool force)
> +
> +{
> + return IRQ_SET_MASK_OK;
> +}
> +
> +static struct irq_chip imx_mu_msi_parent_chip = {
> + .name = "MU",
> + .irq_compose_msi_msg = imx_mu_msi_compose_msg,
> + .irq_set_affinity = imx_mu_msi_set_affinity,
> +};
> +
> +static int imx_mu_msi_domain_irq_alloc(struct irq_domain *domain,
> + unsigned int virq,
> + unsigned int nr_irqs,
> + void *args)
> +{
> + struct imx_mu_msi *msi_data = domain->host_data;
> + msi_alloc_info_t *info = args;
> + int pos, err = 0;
> +
> + pm_runtime_get_sync(&msi_data->pdev->dev);
The core code already deals with runtime PM. What prevents it from
working, other than the fact you don't populate the device in the
top-level domain?
> +
> + WARN_ON(nr_irqs != 1);
> +
> + spin_lock(&msi_data->lock);
> + pos = find_first_zero_bit(&msi_data->used, msi_data->irqs_num);
> + if (pos < msi_data->irqs_num)
> + __set_bit(pos, &msi_data->used);
> + else
> + err = -ENOSPC;
> + spin_unlock(&msi_data->lock);
> +
> + if (err)
> + return err;
> +
> + err = iommu_dma_prepare_msi(info->desc, msi_data->msiir_addr + pos * 4);
> + if (err)
> + return err;
> +
> + irq_domain_set_info(domain, virq, pos,
> + &imx_mu_msi_parent_chip, msi_data,
> + handle_simple_irq, NULL, NULL);
> + return 0;
> +}
> +
> +static void imx_mu_msi_domain_irq_free(struct irq_domain *domain,
> + unsigned int virq, unsigned int nr_irqs)
> +{
> + struct irq_data *d = irq_domain_get_irq_data(domain, virq);
> + struct imx_mu_msi *msi_data = irq_data_get_irq_chip_data(d);
> + int pos;
> +
> + pos = d->hwirq;
> + if (pos < 0 || pos >= msi_data->irqs_num) {
> + pr_err("failed to teardown msi. Invalid hwirq %d\n", pos);
> + return;
> + }
How can this happen?
> +
> + spin_lock(&msi_data->lock);
> + __clear_bit(pos, &msi_data->used);
> + spin_unlock(&msi_data->lock);
> +
> + pm_runtime_put(&msi_data->pdev->dev);
> +}
> +
> +static const struct irq_domain_ops imx_mu_msi_domain_ops = {
> + .alloc = imx_mu_msi_domain_irq_alloc,
> + .free = imx_mu_msi_domain_irq_free,
> +};
> +
> +static void imx_mu_msi_irq_handler(struct irq_desc *desc)
> +{
> + struct imx_mu_msi *msi_data = irq_desc_get_handler_data(desc);
> + u32 status;
> + int i;
> +
> + status = imx_mu_read(msi_data, msi_data->cfg->xSR[IMX_MU_RSR]);
> +
> + chained_irq_enter(irq_desc_get_chip(desc), desc);
> + for (i = 0; i < IMX_MU_CHANS; i++) {
> + if (status & IMX_MU_xSR_RFn(msi_data->cfg->type, i)) {
> + imx_mu_read(msi_data, msi_data->cfg->xRR + i * 4);
> + generic_handle_domain_irq(msi_data->parent, i);
> + }
> + }
> + chained_irq_exit(irq_desc_get_chip(desc), desc);
> +}
> +
> +static int imx_mu_msi_domains_init(struct imx_mu_msi *msi_data)
> +{
> + /* Initialize MSI domain parent */
> + msi_data->parent = irq_domain_add_linear(NULL,
NAK. Don't create anonymous domains.
> + msi_data->irqs_num,
> + &imx_mu_msi_domain_ops,
> + msi_data);
> + if (!msi_data->parent) {
> + dev_err(&msi_data->pdev->dev, "failed to create IRQ domain\n");
> + return -ENOMEM;
> + }
> +
> + msi_data->msi_domain = platform_msi_create_irq_domain(
> + of_node_to_fwnode(msi_data->pdev->dev.of_node),
> + &imx_mu_msi_domain_info,
> + msi_data->parent);
> +
> + if (!msi_data->msi_domain) {
> + dev_err(&msi_data->pdev->dev, "failed to create MSI domain\n");
> + irq_domain_remove(msi_data->parent);
> + return -ENOMEM;
> + }
> +
> + return 0;
> +}
> +
> +static int imx_mu_msi_teardown_hwirq(struct imx_mu_msi *msi_data)
> +{
> + if (msi_data->gic_irq > 0)
> + irq_set_chained_handler_and_data(msi_data->gic_irq, NULL, NULL);
> +
> + return 0;
> +}
> +
> +static const struct imx_mu_dcfg imx_mu_cfg_imx6sx = {
> + .xTR = 0x0,
> + .xRR = 0x10,
> + .xSR = {0x20, 0x20, 0x20, 0x20},
> + .xCR = {0x24, 0x24, 0x24, 0x24},
> +};
> +
> +static const struct imx_mu_dcfg imx_mu_cfg_imx7ulp = {
> + .xTR = 0x20,
> + .xRR = 0x40,
> + .xSR = {0x60, 0x60, 0x60, 0x60},
> + .xCR = {0x64, 0x64, 0x64, 0x64},
> +};
> +
> +static const struct imx_mu_dcfg imx_mu_cfg_imx8ulp = {
> + .type = IMX_MU_V2,
> + .xTR = 0x200,
> + .xRR = 0x280,
> + .xSR = {0xC, 0x118, 0x124, 0x12C},
> + .xCR = {0x110, 0x114, 0x120, 0x128},
> +};
> +
> +static const struct imx_mu_dcfg imx_mu_cfg_imx8ulp_s4 = {
> + .type = IMX_MU_V2 | IMX_MU_V2_S4,
> + .xTR = 0x200,
> + .xRR = 0x280,
> + .xSR = {0xC, 0x118, 0x124, 0x12C},
> + .xCR = {0x110, 0x114, 0x120, 0x128},
> +};
What are these? We really don't need more magic numbers.
> +
> +static const struct of_device_id imx_mu_msi_ids[] = {
> + { .compatible = "fsl,imx7ulp-mu-msi", .data = &imx_mu_cfg_imx7ulp },
> + { .compatible = "fsl,imx6sx-mu-msi", .data = &imx_mu_cfg_imx6sx },
> + { .compatible = "fsl,imx8ulp-mu-msi", .data = &imx_mu_cfg_imx8ulp },
> + { .compatible = "fsl,imx8ulp-mu-msi-s4", .data = &imx_mu_cfg_imx8ulp_s4 },
> + { },
> +};
> +
> +MODULE_DEVICE_TABLE(of, imx_mu_msi_ids);
> +
> +static int imx_mu_msi_probe(struct platform_device *pdev)
> +{
> + const struct of_device_id *match;
> + struct imx_mu_msi *msi_data, *priv;
> + struct device *dev = &pdev->dev;
> + struct resource *res;
> + int ret;
> +
> + match = of_match_device(imx_mu_msi_ids, &pdev->dev);
> + if (!match)
> + return -ENODEV;
> +
> + priv = msi_data = devm_kzalloc(&pdev->dev, sizeof(*msi_data), GFP_KERNEL);
> + if (!msi_data)
> + return -ENOMEM;
> +
> + msi_data->cfg = (struct imx_mu_dcfg *) match->data;
> +
> + msi_data->regs = devm_platform_ioremap_resource_byname(pdev, "a");
> + if (IS_ERR(msi_data->regs)) {
> + dev_err(&pdev->dev, "failed to initialize 'regs'\n");
> + return PTR_ERR(msi_data->regs);
> + }
> +
> + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "b");
> + if (!res)
> + return -EIO;
> +
> + msi_data->msiir_addr = res->start + msi_data->cfg->xTR;
> +
> + msi_data->pdev = pdev;
> + msi_data->irqs_num = IMX_MU_CHANS;
If that's hardcoded, why do we need an extra variable? I also question
the usefulness of this driver if the HW can only deal with *4* MSIs...
This looks a bit like a joke.
> +
> + msi_data->gic_irq = platform_get_irq(msi_data->pdev, 0);
> + if (msi_data->gic_irq <= 0)
> + return -ENODEV;
> +
> + platform_set_drvdata(pdev, msi_data);
> +
> + msi_data->clk = devm_clk_get(dev, NULL);
> + if (IS_ERR(msi_data->clk)) {
> + if (PTR_ERR(msi_data->clk) != -ENOENT)
> + return PTR_ERR(msi_data->clk);
> +
> + msi_data->clk = NULL;
> + }
> +
> + ret = clk_prepare_enable(msi_data->clk);
> + if (ret) {
> + dev_err(dev, "Failed to enable clock\n");
> + return ret;
> + }
> +
> + priv->pd_a = dev_pm_domain_attach_by_name(dev, "a");
> + if (IS_ERR(priv->pd_a))
> + return PTR_ERR(priv->pd_a);
> +
> + priv->pd_link_a = device_link_add(dev, priv->pd_a,
> + DL_FLAG_STATELESS |
> + DL_FLAG_PM_RUNTIME |
> + DL_FLAG_RPM_ACTIVE);
> +
> + if (!priv->pd_link_a) {
> + dev_err(dev, "Failed to add device_link to mu a.\n");
> + return -EINVAL;
> + }
> +
> + priv->pd_b = dev_pm_domain_attach_by_name(dev, "b");
> + if (IS_ERR(priv->pd_b))
> + return PTR_ERR(priv->pd_b);
> +
> + priv->pd_link_b = device_link_add(dev, priv->pd_b,
> + DL_FLAG_STATELESS |
> + DL_FLAG_PM_RUNTIME |
> + DL_FLAG_RPM_ACTIVE);
> +
> + if (!priv->pd_link_b) {
> + dev_err(dev, "Failed to add device_link to mu a.\n");
> + return -EINVAL;
> + }
> +
> + ret = imx_mu_msi_domains_init(msi_data);
> + if (ret)
> + return ret;
> +
> + irq_set_chained_handler_and_data(msi_data->gic_irq,
> + imx_mu_msi_irq_handler,
> + msi_data);
> +
> + pm_runtime_enable(dev);
> +
> + ret = pm_runtime_get_sync(dev);
> + if (ret < 0) {
> + pm_runtime_put_noidle(dev);
> + goto disable_runtime_pm;
> + }
> +
> + ret = pm_runtime_put_sync(dev);
> + if (ret < 0)
> + goto disable_runtime_pm;
> +
> + clk_disable_unprepare(msi_data->clk);
> +
> + return 0;
> +
> +disable_runtime_pm:
> + pm_runtime_disable(dev);
> + clk_disable_unprepare(msi_data->clk);
> +
> + return ret;
> +}
> +
> +static int __maybe_unused imx_mu_runtime_suspend(struct device *dev)
> +{
> + struct imx_mu_msi *priv = dev_get_drvdata(dev);
> +
> + clk_disable_unprepare(priv->clk);
> +
> + return 0;
> +}
> +
> +static int __maybe_unused imx_mu_runtime_resume(struct device *dev)
> +{
> + struct imx_mu_msi *priv = dev_get_drvdata(dev);
> + int ret;
> +
> + ret = clk_prepare_enable(priv->clk);
> + if (ret)
> + dev_err(dev, "failed to enable clock\n");
> +
> + return ret;
> +}
> +
> +static const struct dev_pm_ops imx_mu_pm_ops = {
> + SET_RUNTIME_PM_OPS(imx_mu_runtime_suspend,
> + imx_mu_runtime_resume, NULL)
> +};
> +
> +static int imx_mu_msi_remove(struct platform_device *pdev)
> +{
> + struct imx_mu_msi *msi_data = platform_get_drvdata(pdev);
> +
> + imx_mu_msi_teardown_hwirq(msi_data);
> +
> + irq_domain_remove(msi_data->msi_domain);
> + irq_domain_remove(msi_data->parent);
How do you ensure that no device is still holding interrupts? Let me
give you a hint: you can't. So removing an interrupt controller module
should not be possible.
> +
> + platform_set_drvdata(pdev, NULL);
> +
> + return 0;
> +}
> +
> +static struct platform_driver imx_mu_msi_driver = {
> + .driver = {
> + .name = "imx-mu-msi",
> + .of_match_table = imx_mu_msi_ids,
> + .pm = &imx_mu_pm_ops,
> + },
> + .probe = imx_mu_msi_probe,
> + .remove = imx_mu_msi_remove,
> +};
> +
> +module_platform_driver(imx_mu_msi_driver);
Please use the standard probing methods (IRQCHIP_PLATFORM_DRIVER_BEGIN
and co).
> +
> +MODULE_AUTHOR("Frank Li <Frank.Li@....com>");
> +MODULE_DESCRIPTION("Freescale Layerscape SCFG MSI controller driver");
> +MODULE_LICENSE("GPL");
I have the ugly feeling that this driver really isn't about MSIs, but
is just a way to sneak some terrible abstraction into the kernel... I
guess we'll eventually find out. In the meantime, this driver needs
fixing.
M.
--
Without deviation from the norm, progress is not possible.
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